#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod = 1e9 + 9;
const ll p = 37;
const ll pinv = 297297300;
const int MAXN = 2000010;
int N, ans1, ans2;
int S[MAXN];
ll h[MAXN];
ll ppow[MAXN];
ll ppowinv[MAXN];
ll subhash(int a, int b) {
if (a > b) return 0;
ll res = h[b] - h[a-1];
if (res < 0) res += mod;
res = (res * ppowinv[a]) % mod;
return res;
}
ll combine(int a, int b, int c, int d) {
ll x = subhash(a, b);
ll y = subhash(c, d);
y = (y * ppow[b-a+1]) % mod;
return (x + y) % mod;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
cin >> N;
if (N % 2 == 0) {
cout << "NOT POSSIBLE\n";
return 0;
}
for (int i = 1; i <= N; ++i) {
char ch;
cin >> ch;
S[i] = ch - 'A' + 1;
}
ppow[0] = ppowinv[0] = 1;
for (int i = 1; i <= N; ++i) {
ppow[i] = (ppow[i-1] * p) % mod;
ppowinv[i] = (ppowinv[i-1] * pinv) % mod;
}
h[0] = 0;
for (int i = 1; i <= N; ++i) {
h[i] = (h[i-1] + ppow[i]*S[i]) % mod;
}
ans1 = -1;
for (int i = 1; i <= N; ++i) {
if (i <= N/2) {
if (combine(1, i-1, i+1, (N/2)+1) == subhash((N/2)+2, N)) {
if (ans1 != -1 && subhash(ans1, ans2) != subhash((N/2)+2, N)) {
cout << "NOT UNIQUE\n";
return 0;
}
ans1 = (N/2)+2;
ans2 = N;
}
} else if (i == (N/2)+1) {
if (subhash(1, i-1) == subhash(i+1, N)) {
if (ans1 != -1 && subhash(ans1, ans2) != subhash(1, i-1)) {
cout << "NOT UNIQUE\n";
return 0;
}
ans1 = 1;
ans2 = N/2;
}
} else {
if (subhash(1, N/2) == combine((N/2)+1, i-1, i+1, N)) {
if (ans1 != -1 && subhash(ans1, ans2) != subhash(1, N/2)) {
cout << "NOT UNIQUE\n";
return 0;
}
ans1 = 1;
ans2 = N/2;
}
}
}
if (ans1 == -1) {
cout << "NOT POSSIBLE\n";
} else {
for (int i = ans1; i <= ans2; ++i) {
cout << char(S[i] + 'A' - 1);
}
cout << "\n";
}
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
376 KB |
Output is correct |
| 2 |
Correct |
2 ms |
420 KB |
Output is correct |
| 3 |
Correct |
2 ms |
376 KB |
Output is correct |
| 4 |
Correct |
2 ms |
376 KB |
Output is correct |
| 5 |
Correct |
2 ms |
424 KB |
Output is correct |
| 6 |
Correct |
2 ms |
392 KB |
Output is correct |
| 7 |
Correct |
2 ms |
376 KB |
Output is correct |
| 8 |
Correct |
2 ms |
384 KB |
Output is correct |
| 9 |
Correct |
3 ms |
376 KB |
Output is correct |
| 10 |
Correct |
2 ms |
388 KB |
Output is correct |
| 11 |
Correct |
2 ms |
376 KB |
Output is correct |
| 12 |
Correct |
2 ms |
376 KB |
Output is correct |
| 13 |
Correct |
2 ms |
376 KB |
Output is correct |
| 14 |
Correct |
2 ms |
380 KB |
Output is correct |
| 15 |
Correct |
2 ms |
376 KB |
Output is correct |
| 16 |
Correct |
2 ms |
380 KB |
Output is correct |
| 17 |
Correct |
3 ms |
376 KB |
Output is correct |
| 18 |
Correct |
2 ms |
380 KB |
Output is correct |
| 19 |
Correct |
2 ms |
376 KB |
Output is correct |
| 20 |
Correct |
2 ms |
376 KB |
Output is correct |
| 21 |
Correct |
2 ms |
376 KB |
Output is correct |
| 22 |
Correct |
2 ms |
376 KB |
Output is correct |
| 23 |
Correct |
2 ms |
376 KB |
Output is correct |
| 24 |
Correct |
2 ms |
376 KB |
Output is correct |
| 25 |
Correct |
2 ms |
376 KB |
Output is correct |
| 26 |
Correct |
2 ms |
376 KB |
Output is correct |
| 27 |
Correct |
2 ms |
376 KB |
Output is correct |
| 28 |
Correct |
2 ms |
424 KB |
Output is correct |
| 29 |
Correct |
2 ms |
376 KB |
Output is correct |
| 30 |
Correct |
2 ms |
388 KB |
Output is correct |
| 31 |
Correct |
2 ms |
376 KB |
Output is correct |
| 32 |
Correct |
2 ms |
376 KB |
Output is correct |
| 33 |
Correct |
2 ms |
348 KB |
Output is correct |
| 34 |
Correct |
2 ms |
376 KB |
Output is correct |
| 35 |
Correct |
2 ms |
376 KB |
Output is correct |
| 36 |
Correct |
2 ms |
376 KB |
Output is correct |
| 37 |
Correct |
2 ms |
376 KB |
Output is correct |
| 38 |
Correct |
2 ms |
380 KB |
Output is correct |
| 39 |
Correct |
2 ms |
424 KB |
Output is correct |
| 40 |
Correct |
2 ms |
376 KB |
Output is correct |
| 41 |
Correct |
2 ms |
392 KB |
Output is correct |
| 42 |
Correct |
2 ms |
376 KB |
Output is correct |
| 43 |
Correct |
2 ms |
376 KB |
Output is correct |
| 44 |
Correct |
2 ms |
376 KB |
Output is correct |
| 45 |
Correct |
2 ms |
376 KB |
Output is correct |
| 46 |
Correct |
2 ms |
376 KB |
Output is correct |
| 47 |
Correct |
2 ms |
376 KB |
Output is correct |
| 48 |
Correct |
2 ms |
376 KB |
Output is correct |
| 49 |
Correct |
2 ms |
376 KB |
Output is correct |
| 50 |
Correct |
2 ms |
376 KB |
Output is correct |
| 51 |
Correct |
2 ms |
376 KB |
Output is correct |
| 52 |
Correct |
2 ms |
376 KB |
Output is correct |
| 53 |
Correct |
2 ms |
380 KB |
Output is correct |
| 54 |
Correct |
2 ms |
376 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
173 ms |
58032 KB |
Output is correct |
| 2 |
Correct |
179 ms |
58100 KB |
Output is correct |
| 3 |
Correct |
172 ms |
58096 KB |
Output is correct |
| 4 |
Correct |
174 ms |
58104 KB |
Output is correct |
| 5 |
Correct |
172 ms |
58096 KB |
Output is correct |
| 6 |
Correct |
2 ms |
380 KB |
Output is correct |
| 7 |
Correct |
183 ms |
58096 KB |
Output is correct |
| 8 |
Correct |
135 ms |
51448 KB |
Output is correct |
| 9 |
Correct |
157 ms |
52268 KB |
Output is correct |
| 10 |
Correct |
157 ms |
52272 KB |
Output is correct |
| 11 |
Correct |
123 ms |
47700 KB |
Output is correct |
| 12 |
Correct |
2 ms |
376 KB |
Output is correct |
| 13 |
Correct |
2 ms |
376 KB |
Output is correct |
| 14 |
Correct |
2 ms |
388 KB |
Output is correct |
| 15 |
Correct |
2 ms |
348 KB |
Output is correct |
| 16 |
Correct |
2 ms |
376 KB |
Output is correct |
| 17 |
Correct |
2 ms |
504 KB |
Output is correct |
| 18 |
Correct |
2 ms |
376 KB |
Output is correct |
| 19 |
Correct |
2 ms |
376 KB |
Output is correct |
| 20 |
Correct |
2 ms |
376 KB |
Output is correct |
| 21 |
Correct |
2 ms |
376 KB |
Output is correct |
| 22 |
Correct |
2 ms |
376 KB |
Output is correct |
| 23 |
Correct |
2 ms |
376 KB |
Output is correct |
| 24 |
Correct |
2 ms |
376 KB |
Output is correct |
| 25 |
Correct |
2 ms |
376 KB |
Output is correct |
| 26 |
Correct |
3 ms |
376 KB |
Output is correct |
| 27 |
Correct |
2 ms |
376 KB |
Output is correct |
| 28 |
Correct |
2 ms |
376 KB |
Output is correct |
| 29 |
Correct |
2 ms |
376 KB |
Output is correct |
| 30 |
Correct |
2 ms |
380 KB |
Output is correct |
| 31 |
Correct |
2 ms |
376 KB |
Output is correct |
| 32 |
Correct |
2 ms |
376 KB |
Output is correct |
| 33 |
Correct |
2 ms |
376 KB |
Output is correct |
| 34 |
Correct |
2 ms |
376 KB |
Output is correct |
| 35 |
Correct |
2 ms |
376 KB |
Output is correct |
| 36 |
Correct |
2 ms |
376 KB |
Output is correct |
| 37 |
Correct |
2 ms |
376 KB |
Output is correct |
| 38 |
Correct |
2 ms |
376 KB |
Output is correct |
| 39 |
Correct |
2 ms |
376 KB |
Output is correct |
| 40 |
Correct |
2 ms |
376 KB |
Output is correct |
| 41 |
Correct |
2 ms |
376 KB |
Output is correct |
| 42 |
Correct |
2 ms |
376 KB |
Output is correct |
| 43 |
Correct |
2 ms |
376 KB |
Output is correct |
| 44 |
Correct |
2 ms |
376 KB |
Output is correct |
| 45 |
Correct |
2 ms |
376 KB |
Output is correct |
| 46 |
Correct |
2 ms |
376 KB |
Output is correct |
| 47 |
Correct |
2 ms |
376 KB |
Output is correct |
| 48 |
Correct |
2 ms |
376 KB |
Output is correct |
| 49 |
Correct |
2 ms |
380 KB |
Output is correct |
| 50 |
Correct |
2 ms |
376 KB |
Output is correct |
| 51 |
Correct |
2 ms |
424 KB |
Output is correct |
| 52 |
Correct |
2 ms |
376 KB |
Output is correct |
| 53 |
Correct |
2 ms |
376 KB |
Output is correct |
| 54 |
Correct |
2 ms |
376 KB |
Output is correct |
